IP addresses vary.
The entire point of my phone number, or my email address, is to identify me. Email doesn't get sent "to whoever is interested", it gets sent to designated people. How are those not meant to be identifiers?
The entire point of my phone number, or my email address, is to identify me. Email doesn't get sent "to whoever is interested", it gets sent to designated people. How are those not meant to be identifiers?
They are intended to be delivery points for messages, not identifiers for non-messaging uses. The fact that the two functions are similar does not mean they are identical. Treating them as if they are identical just creates all kinds of (often unexpected) failure modes where the two functions don't overlap.
(Bonus: Yahoo! email addresses get reused too.)
That doesn't affect the fact that the email address exists to identify the person. You'd need to say "people often share email addresses in common", which they don't.
we have a shared email address between us that the kids use, and I use to sign up for some stuff.
My parents have 3 emails addresses between themselves, and use them pretty much interchangeably.
I worked at a distance education provider for a couple of years, and we commonly had entire families using the same email address.
It turns out that when you sign up with an ISP, they give you a single email address by default, and you can - if you wish to, and know how, add more of your own.
Outside of the tech industry, nobody knows how.
For business and organisation IPs, if we get vandalism from that IP, we'll stick it on a long-term block (usually a year) and renew that block if there's recurring vandalism when the block expires.